One time programmable (OTP) electrically programmable read only memory (EPROM) can be an effective, low cost mechanism for providing non-volatile memory in a variety of computer related applications, such as in small handheld digital devices like cellular telephones, personal digital assistants (PDA's), etc.
The OTP EPROM has the advantage of only requiring a small area, for example, about 4 μm2, but can be programmed only once. In addition, OTP EPROM is not electrically erasable without utilizing the expensive and very inconvenient UV erasure technologies.
Single-polysilicon electrically erasable programmable read only memory, herein, (single-poly EEPROM) utilize another simple fabrication process and can be programmed multiple times, but require a large area, for example, of about 50 μm2. This large area is generally needed because of the spacing requirements to accommodate the relatively high voltage requirements of electrically programming and erasing single-poly EEPROM.
Accordingly, it would be desirable to have a relatively small memory device that can be electrically programmed and erased, while utilizing the simpler and lower cost fabrication technology of a single-poly device.